P3355R1 Fix submdspan for C++26

Editorial notes:
 * The editing instructions in the paper do not quite match the actual
   edits that we performed, but this appears to be a deficiency of the
   instructions rather than due to unclear intentions.

Author: tkoeppe

source/containers.tex

@@ -24319,6 +24319,17 @@
 let \tcode{offset} be a value of type \tcode{size_t} equal to
 \tcode{(*this)(\exposid{first_}<index_type, P>(slices...)...)}.
 
+\pnum
+Given a layout mapping type \tcode{M}, a type \tcode{S} is a
+\defnadjx{unit-stride}{slice for \tcode{M}}{slice} if
+\begin{itemize}
+\item \tcode{S} is a specialization of \tcode{strided_slice}
+where \tcode{S::stride_type} models \exposconcept{integral-constant-like}
+and \tcode{S::stride_type::value} equals \tcode{1},
+\item \tcode{S} models \tcode{\exposconcept{index-pair-like}<M::index_type>}, or
+\item \tcode{is_convertible_v<S, full_extent_t>} is \tcode{true}.
+\end{itemize}
+
 \rSec5[mdspan.sub.map.left]{\tcode{layout_left} specialization of \tcode{submdspan_mapping}}
 
 \indexlibrarymemberexpos{layout_left::mapping}{submdspan-mapping-impl}%
@@ -24350,8 +24361,7 @@
   \tcode{is_convertible_v<$S_k$, full_ext\-ent_t>} is \tcode{true}; and
   \item
   for $k$ equal to \tcode{SubExtents::rank() - 1},
-  $S_k$ models \tcode{\exposconcept{index-pair-like}<index_type>} or
-  \tcode{is_convertible_v<$S_k$, full_extent_t>} is \tcode{true};
+  $S_k$ is a unit-stride slice for \tcode{decltype(*this)};
   \end{itemize}
 \begin{note}
 If the above conditions are true,
@@ -24366,21 +24376,17 @@
 \end{codeblock}
 if for a value $u$ for which $u+1$ is
 the smallest value $p$ larger than zero
-for which $S_p$ models
-\tcode{\exposconcept{index-pair-like}<index_type>} or
-\tcode{is_convertible_v<$S_p$, full_extent_t>} is \tcode{true},
+for which $S_p$ is a unit-stride slice for \tcode{decltype(*this)},
 the following conditions are met:
 \begin{itemize}
 \item
-$S_0$ models \tcode{\exposconcept{index-pair-like}<index_type>} or
-\tcode{is_convertible_v<$S_0$, full_extent_t>} is \tcode{true}; and
+$S_0$ is a unit-stride slice for \tcode{decltype(*this)}; and
 \item
 for each $k$ in the range \range{$u$ + 1}{$u$ + SubExtents::rank() - 1},
 \tcode{is_convertible_v<$S_k$, full_extent_t>} is \tcode{true}; and
 \item
 for $k$ equal to \tcode{$u$ + SubExtents::rank() - 1},
-$S_k$ models \tcode{\exposconcept{index-pair-like}<index_type>} or
-\tcode{is_convertible_v<$S_k$, full_extent_t>} is \tcode{true};
+$S_k$ is a unit-stride slice for \tcode{decltype(*this)};
 \end{itemize}
 and where \tcode{S_static} is:
 \begin{itemize}
@@ -24431,8 +24437,7 @@
   \tcode{is_convertible_v<$S_k$, full_extent_t>} is \tcode{true}; and
   \item
   for $k$ equal to \exposid{_rank} - \tcode{SubExtents::rank()},
-  $S_k$ models \tcode{\exposconcept{index-pair-like}<index_type>} or
-  \tcode{is_convertible_v<$S_k$, full_extent_t>} is \tcode{true};
+  $S_k$ is a unit-stride slice for \tcode{decltype(*this)};
   \end{itemize}
 \begin{note}
 If the above conditions are true,
@@ -24447,23 +24452,19 @@
 \end{codeblock}
 if for a value $u$ for which $\exposid{rank_} - u - 2$ is
 the largest value $p$ smaller than \tcode{\exposid{rank_} - 1}
-for which $S_p$ models
-\tcode{\exposconcept{index-pair-like}<index_type>} or
-\tcode{is_convertible_v<$S_p$, full_extent_t>} is \tcode{true},
+for which $S_p$ is a unit-stride slice for \tcode{decltype(*this)},
 the following conditions are met:
 \begin{itemize}
 \item
 for $k$ equal to \tcode{\exposid{rank_} - 1},
-$S_k$ models \tcode{\exposconcept{index-pair-like}<index_type>} or
-\tcode{is_convertible_v<$S_k$, full_extent_t> }is \tcode{true}; and
+$S_k$ is a unit-stride slice for \tcode{decltype(*this)}; and
 \item
 for each $k$ in the range
 \range{\exposid{rank_} - SubExtents::rank() - $u$ + 1}{\exposid{rank_} - $u$ - 1},
 \tcode{is_con\-vertible_v<$S_k$, full_extent_t>} is \tcode{true}; and
 \item
-for $k$ equal to \tcode{\exposid{rank_} - SubExtents::rank() - $u$},
-$S_k$ models \tcode{\exposconcept{index-pair-like}<index_type>} or
-\tcode{is_convertible_v<$S_k$, full_extent_t>} is \tcode{true};
+for $k$ equal to \tcode{\exposid{rank_} - SubExtents::rank() - $u$},\newline
+$S_k$ is a unit-stride slice for \tcode{decltype(*this)};
 \end{itemize}
 and where \tcode{S_static} is:
 \begin{itemize}
@@ -24539,8 +24540,7 @@
 \item
 \tcode{SubExtents::rank() == 1} is \tcode{true} and
 \item
-$S_0$ models \tcode{\exposconcept{index-pair-like}<index_type>} or
-\tcode{is_convertible_v<$S_0$ , full_extent_t>} is \tcode{true};
+$S_0$ is a unit-stride slice for \tcode{decltype(*this)};
 \end{itemize}
 \item
 otherwise,
@@ -24550,20 +24550,17 @@
 \end{codeblock}
 if for a value $u$
 for which \tcode{$u$ + 1} is the smallest value $p$ larger than zero
-for which $S_p$ models \tcode{\exposconcept{index-pair-like}<index_type>} or
-\tcode{is_convertible_v<$S_p$, full_extent_t>} is \tcode{true},
+for which $S_p$ is a unit-stride slice for \tcode{decltype(*this)},
 the following conditions are met:
 \begin{itemize}
 \item
-$S_0$ models \tcode{\exposconcept{index-pair-like}<index_type>} or
-\tcode{is_convertible_v<$S_0$, full_extent_t>} is \tcode{true}; and
+$S_0$ is a unit-stride slice for \tcode{decltype(*this)}; and
 \item
 for each $k$ in the range \range{$u$ + 1}{$u$ + SubExtents::rank() - 1},
 \tcode{is_convertible_v<$S_k$, full_extent_t>} is \tcode{true}; and
 \item
 for $k$ equal to \tcode{$u$ + SubExtents::rank() - 1},
-$S_k$ models \tcode{\exposconcept{index-pair-like}<index_type>} or
-\tcode{is_convertible_v<Sk, full_extent_t>} is \tcode{true};
+$S_k$ is a unit-stride slice for \tcode{decltype(*this)};
 \end{itemize}
 where \tcode{S_static} is:
 \begin{itemize}
@@ -24615,8 +24612,7 @@
 \tcode{SubExtents::rank() == 1} is \tcode{true} and
 \item
 for $k$ equal to \tcode{\exposid{rank_} - 1},
-$S_k$ models \tcode{\exposconcept{index-pair-like}<index_type>} or
-\tcode{is_convertible_v<$S_k$ , full_extent_t>} is \tcode{true};
+$S_k$ is a unit-stride slice for \tcode{decltype(*this)};
 \end{itemize}
 \item
 otherwise,
@@ -24627,22 +24623,19 @@
 if for a value $u$
 for which \tcode{\exposid{rank_} - $u$ - 2}
 is the largest value p smaller than \tcode{\exposid{rank_} - 1}
-for which $S_p$ models \tcode{\exposconcept{index-pair-like}<index_type>} or
-\tcode{is_convertible_v<$S_p$, full_extent_t>} is \tcode{true},
+for which $S_p$ is a unit-stride slice for \tcode{decltype(*this)},
 the following conditions are met:
 \begin{itemize}
 \item
 for $k$ equal to \tcode{\exposid{rank_} - 1},
-$S_k$ models \tcode{\exposconcept{index-pair-like}<index_type>} or
-\tcode{is_convertible_v<$S_k$, full_extent_t>} is \tcode{true}; and
+$S_k$ is a unit-stride slice for \tcode{decltype(*this)}; and
 \item
 for each $k$ in the range
 \range{\exposid{rank_} - SubExtents::rank() - $u$ + 1}{\exposid{rank_} - $u$ - 1)},
 \tcode{is_convertible_v<$S_k$, full_extent_t>} is \tcode{true}; and
 \item
-for $k$ equal to \tcode{\exposid{rank_} - SubExtents::rank() - $u$},
-$S_k$ models \tcode{\exposconcept{index-pair-like}<index_type>} or
-\tcode{is_convertible_v<$S_k$, full_extent_t>} is \tcode{true};
+for $k$ equal to \tcode{\exposid{rank_} - SubExtents::rank() - $u$},\newline
+$S_k$ is a unit-stride slice for \tcode{decltype(*this)};
 \end{itemize}
 and where \tcode{S_static} is:
 \begin{itemize}

source/support.tex

@@ -797,7 +797,7 @@
 #define @\defnlibxname{cpp_lib_string_resize_and_overwrite}@       202110L // also in \libheader{string}
 #define @\defnlibxname{cpp_lib_string_udls}@                       201304L // also in \libheader{string}
 #define @\defnlibxname{cpp_lib_string_view}@                       202403L // also in \libheader{string}, \libheader{string_view}
-#define @\defnlibxname{cpp_lib_submdspan}@                         202403L // freestanding, also in \libheader{mdspan}
+#define @\defnlibxname{cpp_lib_submdspan}@                         202411L // freestanding, also in \libheader{mdspan}
 #define @\defnlibxname{cpp_lib_syncbuf}@                           201803L // also in \libheader{syncstream}
 #define @\defnlibxname{cpp_lib_text_encoding}@                     202306L // also in \libheader{text_encoding}
 #define @\defnlibxname{cpp_lib_three_way_comparison}@              201907L // freestanding, also in \libheader{compare}